Antioch explores building desalination plant

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The Encina power plant is positioned across from the beach in central Carlsbad where cool seawater is used to cool the plant. The new Carlsbad desalination plant is being built behind the power plant and will use the water that is being used by Encina and turn it into drinking water. When completed in 2016, it will be the largest desalination plant in the Western Hemisphere and will produce 50 million gallons per day and will supplement the regional water supply. (Photo by Scott Varley/Media News Group)

ANTIOCH — City officials are exploring whether Antioch can turn the salty Delta water off its shoreline into a true liquid asset by building a desalination plant.

The idea is for the city to take the brackish water it draws from the San Joaquin River and turn it into quality water for residents to drink, potentially luring businesses that need consistent, pure water.

“Basically, what we’re doing is our due diligence to see if it makes sense financially,” said Ron Bernal, the city’s director of public works.

Antioch has rights dating before 1914 to pump water without the need for a state permit, and through an agreement with the state’s Department of Water Resources that dates to 1968, it can draw water from the San Joaquin River 208 days a year.

The idea of leveraging those rights has been floated for years, but this year’s severe drought prompted Antioch officials to “take it off the back-burner,” City Manager Steve Duran said.

The raw water Antioch pumps has been undrinkable in recent months because of higher levels of salinity, Bernal said. Antioch has had to use water exclusively from the Contra Costa Water District and tap into its reserve fund to cover the additional cost, he said.

Delta Diablo Sanitation District, which treats Antioch’s wastewater, is working with the city on the idea, offering to take the brine byproduct left from desalination and dispose it as part of its other processes. That process is often costly, and has brought some desalination efforts around the state to a halt.

“It’s intriguing. The western Delta is an untapped resource. With the help of these new technologies, it could be a potential game-changer,” General Manager Gary Darling said.

Delta Diablo is also lending its assistance to connect Antioch with funding and help the city look at research being done to reduce costs.

Antioch is looking at some methods being studied by Lawrence Livermore National Laboratory that specifically reduce the amount of energy used in desalination, Duran said. The flow-through desalination would remove the salt electrically.

Enormous energy costs to force the water through large filters has been a dealbreaker for desalination efforts over the years.

Unlike the ocean desalination projects elsewhere in the state, the level of solids that would need to be treated are significantly less in the western Delta, Darling said. The Pacific Ocean has a salt level of about 30,000 parts per million, and the San Joaquin River averages about one-third of that, he said.

Antioch leaders indicated their support at a recent City Council meeting.

“It’s a major project, but I think it’s a great one to venture into,” Mayor Pro Tem Mary Rocha said at the May 27 meeting.

Councilman Gary Agopian said the idea could put the city “on the cutting edge.”

“We need to be full-steam ahead on this idea. Knowing the limitations on water, and what’s happening in the future, it’s never going to be like how it was before,” Agopian said. “We’re fighting over droplets.”

Antioch won’t have to look far to see how a plant could work.

A few miles to the west near Bay Point, a group of Bay Area water agencies, including Contra Costa Water District, East Bay Municipal Utility District and Zone 7 Water Agency, had been looking into a possible $200 million desalination plant that could pump up to 20 million gallons of water a day.

A pilot was tested in 2009 at Mallard Slough. The plans, however, were shelved earlier this year when group members decided they could obtain water more cheaply through recycling and other means.